Firing mechanism for a pyrotechnic device

ABSTRACT

An improved mechanical firing mechanism of the kind in which a spring-urged striker pin is employed for detonating a percussion igniter in a pyrotechnic device. The mechanism comprises a manually actuated lever pivotally attached to the striker pin and employed to prime a striker spring in a first part of its movement and to release the primed striker pin when the lever is aligned with the striker pin.

Unite tates ate [1 1 3,640,012 Schermuly Feb. 8, 1972 [54] FIRING MECHANISM FOR A 3,051,085 8/1962 0 Finkelstein ..102/37.8 PYROTECHNIC D VICE 2,961,962 11/1960 Jackson ..l02/37.8 3,386,334 6/1968 Temple et a1. ..42/l R [72] Inventor: Alfred James Schermuly, Windswept Kingd near D l, K t, E la d FOREIGN PATENTS OR APPLICATIONS [22] Filed: Mar. 27, 1970 1,245,193 9/1960 France ..89/1 B PP 23338 Primary Examiner-Benjamin A. Borchelt Assistant Examiner-C. T. Jordan [30] Foreign Application Priority Data AttarneyM1chael S. Striker Mar. 31, 1969 Great Britain l6,683/69 [57] ABSTRACT An improved mechanical firing mechanism of the kind in [52] US. CL ..42/1 R, 89/1 B, 102/374 which a springmrged striker pin is employed for detonafing a [51] [111. Cl. ..F41C 19/00 percussion igniter in a pyrotechnic device The mechanism [58] Field of Search ..42/69 R, 1 R, 1 F, 1 G, l H, comprises a manually actuated [ever Pivotal, attached to the 42/1 J, 1 M, 1 Z; 89/1 B, 1 R; 102/37.4, 37.8, 6 striker pin and employed to prime a striker spring in a first part of its movement and to release the primed striker pin when the lever is aligned with the striker pin. [56] References Cited 5 Claims, 2 Drawing Figures UNITED STATES PATENTS 3,331,397 11/1970 Ripley et al ..102/37.8

FIRING MECHANISM FOR A PYROTECWIC DEVHGE This invention relates to an improved spring-urged mechanical firing mechanism for pyrotechnic devices such as rockets (line carrying or distress signal rockets), hand-held flare or smoke distress signals, aircraft-home flares or buoyant marine illuminating or smoke signaling devices.

Spring-urged mechanical firing mechanisms are known in which the energy necessary to drive a striker pin against a percussion cap or detonator is stored in a priming spring (usually a helical spring surrounding the striker pin) to be liberated when the striker pin is released, the priming of the spring (i.e., the accumulation of the necessary stored energy in the spring) is effected only as a safety catch is moved to a firing position to release the striker pin. A firing mechanism of the kind described will be referred to in this specification as a normally unprimed firing mechanism and has the advantage over preprimed firing mechanisms (i.e., mechanisms in which the priming spring is primed throughout storage) in that they are safer and in that there is less likelihood of the priming spring becoming weakened to the point of being incapable of imparting sufficient energy to the striker pin to fire the detonator.

This invention relates to a normally unprimed firing mechanism which is of simple construction, is cheap to manufacture and which can be used repeatedly merely by replacing a spent detonator with a new live one.

According to the invention a normally unprimed firing mechanism comprises a housing having a bore therein, a striker pin slidably contained within the bore, means to hold a percussion cap or detonator at one end of the bore, a priming spring within the bore surrounding the striker pin, with one end engaging the housing and the other end engaging the striker pin to urge the latter towards said one end of the bore, and a priming/release lever pivotally secured to the striker pin about a pivoting axis and intermediate the ends of the priming/release lever, the priming/release lever serving (a) to retain the striker pin in spaced relation to the cap or detonator by engagement of both ends thereof with the housing when the lever extends transversely of the axis of the striker pin, (b) to compress the priming spring as the priming/release lever is turned about the pivoting axis towards a position of alignment with the axis of the striker pin and (c) to allow the striker pin to fire the cap or detonator as at least a part of the priming/release lever passes into said bore when in its position of alignment.

Conveniently the primingrelease lever is located in a groove in the housing before a priming and release action is commenced, that end of the priming/release lever, which bears against the groove when the priming/release lever is being turned about the pivoting axis, preferably being curved to facilitate turning of the priming/release lever against the force exerted by the priming spring during its compression.

Preferably the priming/release lever is secured to the striker pin in a bifurcated end thereof so that the prirningjrelease lever lies within the cross-sectional area of the striker pin when the priming/release lever is in its position of alignment.

One embodiment of normally unprimed firing mechanism in accordance with the invention will now be described, by way of example, with reference to the accompanying drawing, in which:

FIG. 1 is a partially sectioned perspective view of the firing mechanism, and

HG. 2 is a perspective view on a reduced scale showing a pyrotechnic device equipped with the mechanism shown in FIG. 1.

Referring to FIG. 1 of the drawing, a housing, formed from an apertured top plate 1 and a tubular barrel 2, contains a striker pin 3 and a helical priming spring 4. A percussion cap 5 is clamped at one end of the barrel 2 by a threaded cup 6. The end of the striker pin 3 closest to the cap 5 is provided with a firing point 7 which is maintained in spaced relation to the cap 5 by a priming/release lever 8 pivotally secured between bifurcation at the upper end of the striker pin 3 by a pivot peg 9.

The priming spring 4 is lightly compressed when the mechanism is in the condition shown in FIG. I and the striker pin 3 is prevented from moving towards the cap 5 by engagement of each end of the lever 8 with the bottom of a groove 10 formed in the plate 1.

On turning the lever 8 about the pivot peg 9 in the direction of the arrow A, the pin 3 is lifted away from the cap 5 (thus further compressing the spring 4) until the position shown in dotted lines is reached, when the lower end of the lever 8 is contained within the cross section of the bifurcated end of the pin 3. The pin 3 is now released and under the influence of the stressed spring 4, the lower end of the lever 8 follows the pin 3 into the bore of the barrel 2 (in the direction of the arrow B) to permit the point 7 to fire the cap 5.

An important feature of the mechanism illustrated is that it can be reused merely by withdrawing the upper end of the pin 3 from the barrel, restoring the lever B to its original position in the groove 10, unscrewing the cup 6 and replacing the spent cap 5 by a new one. The ratio between the lengths of the lever 8 on either side of the pivot peg 9 determines the mechanical advantage available for compressing the spring 4 and this mechanical advantage should be as large as possible commensurate with the desired overall length of lever 8 and the upward movement of the pin 3 necessary to adequately compress the spring 4. To facilitate the turning of the lever 8, the shorter end 11 which engages the bottom of the groove is curved. The lower surface of the groove 10 contacted by the end llll may also be curved to facilitate firing operations.

FIG. 2 shows a distress rocket 12 located within a cylindrical casing 13. One end of the casing 13 is formed by the plate 1 and the other end is covered (in known manner) by a removable lid 14. The barrel 2 of the firing mechanism protrudes into the trailing end of the rocket 12 so that the flash from the cap 5 can fire the rocket motor, (shown dotted at 15). To enable the cap 5 to be replaced, the casing 13 can be removably attached to the plate I, the join between the two parts being at 16.

If it is desired to use the mechanism described above with a static line, it is convenient to surround the priming/release lever 8 with a sleeve which is slotted at its inner end (the slots accommodate the pivot peg 9) and extends beyond the lever 8 at its outer end, the projecting portion of the sleeve being apertured to receive an end of the static line. The sleeve is secured to the lever 8 in such a manner that the force necessary to remove the sleeve from the lever exceeds the force necessary to turn the lever 8 into its firing position. In this way when tension is applied to the static line (in the general direction of the arrow A) the mechanism is primed and fired before the sleeve is torn off the lever.

To improve the temporary securement of the sleeve on the priming/release lever a shear wire may be employed to inter connect the two, the wire being strong enough to withstand the force necessary to turn the lever 8 into the firing position but breaking on the application of forces in excess of this.

What is claimed is:

I. A normally unprimed firing mechanism comprising a housing heaving a bore therein, a striker pin slidably contained within the bore, means to hold a percussion cap or detonator at one end of the bore, a priming spring within the bore surrounding the striker pin, with one end engaging the housing and the other end engaging the striker pin to urge the latter towards said one end of the bore, and a printing/release lever pivotally secured to the striker pin about a pivoting axis and intermediate the ends of the priming/release lever, the priming/release lever serving a. to retain the striker pin in spaced relation to the cap or detonator by engagement of both ends thereof with the housing when the lever extends transversely of the axis of the striker pin,

b, to compress the priming spring as the priming/release lever is turned about the pivoting axis towards a position of alignment with the axis of the striker pin and,

c. to allow the striker pin to fire the cap or detonator as at least a part of the priming/release lever passes into said bore when in its position of alignment.

2 A firing mechanism as claimed in claim 1 in which the priming/release lever is located in a groove in the housing before a priming and release action is commenced.

3. A firing mechanism as claimed in claim 2, in which that end of the priming/release lever, which bears against the groove when the priming/release lever is being turned about the pivoting axis, is curved to facilitate turning of the priming/release lever against the force exerted by the priming spring during its compression.

4. A firing mechanism as claimed in claim 1, in which the priming/release lever is secured to the striker pin in a bifurcated end thereof so that the priming/release lever lies within the cross-sectional area of the striker pin when the priming/release lever is in its position of alignment.

5. A firing mechanism as claimed in claim 1, in which the detonator is held at said one end of the bore by a removable cup. 

1. A normally unprimed firing mechanism comprising a housing heaving a bore therein, a striker pin slidably contained within the bore, means to hold a percussion cap or detonator at one end of the bore, a priming spring within the bore surrounding the striker pin, with one end engaging the housing and the other end engaging the striker pin to urge the latter towards said one end of the bore, and a priming/release lever pivotally secured to the striker pin about a pivoting axis and intermediate the ends of the priming/release lever, the priming/release lever serving a. to retain the striker pin in spaced relation to the cap or detonator by engagement of both ends thereof with the housing when the lever extends transversely of the axis of the striker pin, b. to compress the priming spring as the priming/release lever is turned about the pivoting axis towards a position of alignment with the axis of the striker pin and, c. to allow the striker pin to fire the cap or detonator as at least a part of the priming/release lever passes into said bore when in its position of alignment.
 2. A firing mechanism as claimed in claim 1 in which the priming/release lever is located in a groove in the housing before a priming and release action is commenced.
 3. A firing mechanism as claimed in claim 2, in which that end of the priming/release lever, which bears against the groove when the priming/release lever is being turned about the pivoting axis, is curved to facilitate turning of the priming/release lever against the force exerted by the priming spring during its compression.
 4. A firing mechanism as claimed in claim 1, in which the priming/release lever is secured to the striker pin in a bifurcated end thereof so that the priming/release lever lies within the cross-sectional area of the striker pin when the priming/release lever is in its position of alignment.
 5. A firing mechanism as claimed in claim 1, in which the detonator is held at said one end of the bore by a removable cup. 